The present invention relates to an airbag that is installed in a vehicle to protect an occupant of the vehicle.
For example, Japanese Examined Patent Publication No. 6-47363 discloses an airbag that is deployed to a predetermined position. Specifically, when protecting an occupant of a vehicle, the airbag is deployed and inflated while contacting structures in the passenger compartment, such as an instrument panel, a windshield, and a pillar garnish. Contacting the structures allows the airbag to be held at the predetermined position.
The airbag of the publication has vent holes for discharging gas that is supplied to the airbag for inflation and deployment to the outside. The vent holes prevent the internal pressure from being excessively increased, thereby effectively holding and protecting an occupant. Normally, the positions of the vent holes are determined such that discharged gas is directed away from the occupant.
When protecting an occupant, a typical airbag is pushed back by the occupant in a direction opposite to the direction of inflation and deployment. In other cases, the airbag is moved laterally. Accordingly, the airbag can contact structures in the passenger compartment at a relatively large area. This sometimes causes the vent holes to be partly or entirely blocked by the contacting structures. When blocked, the vent holes cannot smoothly discharge gas. It is thus difficult to improve the occupant protection performance of the airbag.